Numerous pyrido2,3-d!pyrimidines are known. For example, U.S. Pat. No. 3,534,039 discloses a series of 2,7-diamino-6-arylpyrido2,3-d!pyrimidine compounds as diuretic agents; U.S. Pat. No. 3,639,401 discloses a series of 6-aryl-2,7-bis(trialkylsilyl)amino!-pyrido2,3-d!pyrimidine compounds as diuretic agents; U.S. Pat. No. 4,271,164 discloses a series of 6-substituted-arylpyrido2,3-d!pyrimidin-7-amines and derivatives as antihypertensive agents; European Published Application 0 537 463 A2 discloses a series of substituted-pyrido2,3-d!pyrimidines useful as herbicides. More recently, WO96/34867 teaches a group of 2-amino-pyrido2,3-d!pyrimidines which are useful for treating atherosclerosis, restenosis, psoriasis, and cancer. This invention provides N-oxides of certain tertiary amino containing 2-amino-pyrido2,3-d!pyrimidines. The N-oxides are metabolites of the corresponding tertiary. amino compounds that also inhibit kinase enzymes.